Electric immersion heater assembly



1963 L. D. DRUGMAND ELECTRIC IMMERSION HEATER ASSEMBLY Filed June 8, 1960 M m mm w M M 9 o J r ,z A m a M M 2 z M 0 3 I mT d 1 United States Patent 3,111,572 ELECTREC EMMERSHQN HEATER ASSEMBLY Lester D. Drugmand, Pittsburgh, Pa, assignor to Edwin lb. Wiegand Company, Pittsburgh, Pa. Filed June 8, 1960, Ser- No. 34,723 4 Claims. (Cl. 219-38) My invention relates to electric heaters, more particularly to hot water heaters, and the principal object of my invention is to provide new and improved heaters of this character.

My invention is particularly suitable for hot water heaters and it will be described in this connection, although it is to be understood that the invention is not limited to such use.

For a time, electric heaters of the immersion type were largely used to heat the contents of a hot water tank because of the good heat transfer relationship between the heater and the Water in the tank. Then, because of various reasons, electric heaters of the so-ca-lled wraparound type became popular and although such heaters solved some of the problems theretofore presented, the efliciency of the tank heated by a wrap-around heater suffered because the heater usually employed inica insulation which limited the watt density of the heater and also because of the difliculty in maintaining reasonably good thermal transfer between the heater and the tank wall.

Recently, the industry has returned to the immersion type electric heater because of its efiiciency but since this type of heater required a water-tight connection with the tank, the matter of cost was still a major item.

i-leretofore, a metal collar was secured into an opening in the tank wall by a water-tight weld between the outer peripheral surface of the collar and the adjoining marginal surface of the tank wall. This involved costly parts and considerable skilled labor and thus was expensive. My invention eliminates the requirement for such parts and labor and provides a construction which lends itself to automation; thereby to reduce the overall cost of the entire assembly. However, my invention provides still combination with the metal collar heretofore used and therefore adapts well to replacement purposes.

in the drawirn accompanying this specification and forming a part of this application, there is shown, for purposes of illustration, an embodiment which my inventicn may assume, and in this drawing:

FlGURE 1 is a separated perspective view showing a presently preferred embodiment of my invention, the hot water tank being shown fragmentarily,

FIGURE 2 is a transverse sectional view taken through my improved construction, disclosing one method of connecting to a water tank, and

FIGURE 3 is a sectional view similar to FIGURE 2 but showing another method of connecting to a water tank.

Referring first to FIGURE 3, a previously preferred method of securing an electric immersion heater to a tank included use of a metal collar ill partially disposed through an opening it in the side wall 112. of the hot water tank or other fiuid container. The collar ltl had a conical wall 14 which engaged against that part of the adjoining wall surface :na-rgining the opening ill and, to insure against leaka e of fiuid, a fluid-tight weld 15 was made completely around the collar to join it to the tank wall. The flange of an electric immersion heater was then bolted to the collar to compress a gasket interposed between surfaces of the collar and flange.

The foregoing construction involved considerable expense, not only in the cost of the collar ill which was usually formed as a rough forging and machined to 3,111,572 Patented Nov. 19, 1963 usable condition, but also because of the expense involved in making the fluid-tight weld 15.

My invention eliminates the need for the expensive collar and weld and thus materially reduces cost, to the great benefit of the ultimate purchaser and user. At the same time, my invention provides for combination with the collar type connection and therefore does not cause any replacement problems for water heaters now on the market or in use.

The presently preferred embodiment of my invention comprises a metal support plate 2h which may be formed as a stamping at a high production rate. The support plate is here shown as flat and rectangular (square) in plan, with a central, preferably circular, opening 21 of a size larger in diameter than the diameter of the opening 22 in the wall 23 of the tank. The support plate may have welding projections (not shown) extending from that face which is directed toward the tank wall 23 to enable the plate to be resistance welded to the wall, as shown at 24' in FI URE 2, or plain spot welds may be used to effect the connection. No attempt need be made to establish fluid tight connection between the supporting plate 2%? and the tank wall 23, as will be evident. The only requirement of the connection between the plate and tank wall is that the two are adequately joined against unintentional separation and thus the method of connecting the two may be variously changed to suit requirements. For example, the plate 2d may be tack welded to the tank wall by are welds extending only partially along opposite edges of the plate.

The larger opening 21 exposes a circular lip- 25 pro vided by that part or" the tank wall which margins the wall opening 22 and this lip forms a gasket surface. Since the area defining the asket surface is relatively small as compared to diameter of the tank, the wall curvature adiacent the opening 22 is negligible. However, if desired, the tank wall at the opening 22 :may be flattened, as shown at 26 in FlGURE 1, and this flattening operation may be performed 'at the time the hole 22 is punched in the tank wall.

The presently preferred embodiment of my invention includes a mounting plate 27 preferably having -a flange 223 which may be rectangular in plan to correspond :to the shape of the support plate 2d. The mounting plate 27 has a central inwardly dished conical portion 29 to provide an outwardly directed conical recess 3% for a purpose later to be disclosed. The dished portion 29 terminates in a flat circular wall 31, the outer surface 32 of which is formed toprovide a gasket surface adapted to adjoin and face the circular lip 25 and to compress a ring-like gasket 33 therebetween.

The terminal legs 34, 34 of a sheathed electric heating element 3:; pass through the wall 31 in fluid tight relation and rigidly support the heater on the mounting plate 27'. Terminal pins 36, 36, which are connected to opposite ends of tun electrical resistor (not shown) extend from respective terminal legs 34 and are connectable to a suitable source or" power in any desired manner. The heating element is preferably of the hair-pin type such, for example, as shown in the patent to H. C. Dicome, 2,810,815.

Any suitable means may be provided to maintain elec trical separation between the terminal pins 36, 36. In FIGURE 2, the conical recess is substantially filled with an epoxy resin 37; in FIGURE 3, a porcelain insulator block 38 may be disposed over and about the terminal pins. 'In either case, it will be appreciated that the terminal structure of the heater does not materially extend beyond the flange of the mounting plate.

The support plate 29 is formed with screw threaded openings 49 and the mounting plate 27 is formed with aligned openings 41 in the flange 28 thereof. Bolts 52 pass through openings 41 and are threaded into aligned openings 40 to compress the gasket 33 and thus effectively seal against leakage of fluid at this point.

In the event the heater is to replace a heater taken from a prior tank mounting, the gasket 33 is not used but an additional ring-like gasket 43 is used. The gasket 43 is formed with an opening 44 of a diameter slightly smaller than the larger exterior diameter of the conical portion 29 so that the gasket will have a friction fit with the portion 29 and thereby be supported for shipment and handling. The gasket 43 has holes 45 for passing the bolts 42 and the latter are threaded into holes (not shown) formed in the collar and corresponding to the holes iii of the mounting plate 2'7.

Thus, the electric heater may be mounted on either the support plate or the collar it), the only change being in the gaskets 33 or 43.

In view of the foregoing it will be apparent to these skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. The combination of a hot water tank and an electric immersion heater for heating the contents of said tank, said tank having a circular opening in a defining wall and having a flat metallic support plate welded to said wall and disposed exteriorly thereof, said support plate having a circular opening therethrough which is aligned with but is larger than the tank opening so as to leave exposed a circular lip provided by the tank wall surface margining said tank opening, and said heater including a sheathed electric heating element extending through said tank opening and into said tank and a metallic mounting plate rigidly secured to said sheath and extending crosswise thereof, s-aid mounting plate having a flat portion overlying said support plate and a circular portion disposed within the opening of said support plate and provided with a gasket surface disposed adjacent to said circular lip, a gasket interposed between said gasket surface and said circular lip, and screw means between said support and mounting plates to draw said mounting plate closely to said support plate and thereby compress said gasket to seal against water leakage through said wall opening.

2. The combination of a hot Water tank and an electric immersion heater for heating the contents of said tank, said tank having a circular opening in a side wall and having a flat rectangularly shaped support plate welded to the exterior of said side wall, said support plate having a circular opening therethrough which is aligned with but is larger than the tank opening so as to leave exposed a circular lip provided by the tank wall surface margining said tank opening and said support plate also having a screw-threaded aperture in each of its four corner portions, and said heater includes a sheathed electric heating element extending through said tank opering and into said tank and a metallic mounting plate rigidly secured to said sheath and extending crosswise thereof, said mounting plate having a flat rectangularly shaped portion corresponding to and overlying said support plate and having corner openings to match and align with the screw-threaded support plate openings, and said mounting plate having a central circular portion extending from the rectangularly shaped portion and into the opening of said support plate and terminating in a flat gasket surface in juxtaposed relation with said circular lip, a ring-like gasket interposed between said gasket surface and said circular lip, and headed screws passing through the openings in 4 said mounting plate and threaded into the corresponding aligned screw-threaded openings in said mounting plate to draw said mounting plate closely to said support plate and thereby compress said gasket to seal against water leakage through said Wall opening.

3. An electric heater assembly for selective use with water tanks having an apertured side wall for reception therethrough of a heating element projecting internally of said tank, wherein said tanks are of:

(l) a first type having a substantially annular heating assembly support means secured to said tank wall externally thereof in spaced substantially surrounding relation to the tank wall aperture, said support means having an external exposed end face and having an internal diameter greater than the diameter of the tank wall aperture so as to define an annular lip on said tank wall between said support means and said aperture to form a gasket surface, an annular gasket overlying said lip and surrounding said aperture, and means for detachably securing said heater assembly to said exposed end face of said support means; or

(2) a second type having an annular heating assembly support means secured to the tank Wall at its aperture and extending externally thereof, said support means having an exposed end face and an internal diameter greater than the diameter of said first type tank wall aperture and substantially equal to the internal diameter of said first type support means, an annular gasket surface on the exposed end face of said second type support means, and means for detachably securing said heater assembly to said exposed end face;

said heater assembly including a sheathed electric heating element of lesser transverse dimension than the diameter of said wall aperture of said first type tank, and a surrounding mounting member secured transversely thereof intermediate the ends thereof in liquidtight relation,

said mounting member having a first annular gasket surface thereon of lesser diameter than the internal diameters of the support means of said first and second tank types and of greater diameter than the diameter of the wall aperture of the first tank type,

said mounting member further having a second annular gasket surface thereon axially spaced from and outwardly concentric with said first gasket surface, said second gasket surface being of such size as to overlie a substantial portion of said exposed end faces of said support means of the first and second tank types,

said mounting member having an axially extending wall interconnecting said gasket surfaces thereof, said wall having an axial length substantially equal to that of the external support means of said first tank type, and an external diameter lesser than the internal diameters of said support means of the first and second tank types,

whereby said mounting member may be selectively secured by said securing means to said support means of said first tank type to clamp said gasket therefor between said first gasket surface and said wall lip, or to said support means of said second tank type to clamp said gasket therefor between said second gasket surface of said mounting member and said gasket surface of said first tank type support means, thereby to seal either tank type against leakage through the apertured wall thereof.

4. in combination: a metal tank having a thin substantially uniform-thickness wall formed with a circular opening, an electric heater for heating the contents of said tank, a metallic support member welded to the exterior of said wall in surrounding relation to said tank opening and reenforcing the tank wall thereat, said support member having an opening therethrough coaxial with and of a greater diameter than said tank opening to leave exposed an annular exterior wall surface margining said container aperture and forming an annular gasket lip, it being neces sary only to weld said support member to said tank Wall for good mechanical connection without requiring a fluidtight connection therebetween, a mounting plate and a sheathed electric heating element extending normally of said mounting plate and in liquid-tight relation through an opening in the latter with an active heating portion projecting from an inner side of said mounting plate and disposed within said tank and a terminal portion projecting from the outer side of said mounting plate for conneetion to a source of electrical energy, a ring gasket concentric with and disposed within said support member opening and having one side seated against said annular lip and its opposite side engaging the inner side of said mounting plate, and means connecting said mounting plate and said support member for drawing said mounting plate toward said gasket lip to compress said gasket therebetween and thus seal said tank opening against leakage of fluid therethrough.

References Cited in the file of this patent UNITED STATES PATENTS Williams Aug. 30, Hyatt Mar. 19, Randolph Apr. 18, Charbonneau May 31, Char-bonneau Apr. 22, Bremer Nov. 18, Thomas Mar. 2, Dicome Oct. 22, Fox Nov. 11, Fox Aug. 2, Fischer Oct. 2,

FOREIGN PATENTS Great Britain Mar. 24, Great Britain Feb. 23, Great Britain Nov. 23, 

4. IN COMBINATION: A METAL TANK HAVING A THIN SUBSTANTIALLY UNIFORM-THICKNESS WALL FORMED WITH A CIRCULAR OPENING, AN ELECTRIC HEATER FOR HEATING THE CONTENTS OF SAID TANK, A METALLIC SUPPORT MEMBER WELDED TO THE EXTERIOR OF SAID WALL IN SURROUNDING RELATION TO SAID TANK OPENING AND REENFORCING THE TANK WALL THEREAT, SAID SUPPORT MEMBER HAVING AN OPENING THERETHROUGH COAXIAL WITH AND OF A GREATER DIAMETER THAN SAID TANK OPENING TO LEAVE EXPOSED AN ANNULAR EXTERIOR WALL SURFACE MARGINING SAID CONTAINER APERTURE AND FORMING AN ANNULAR GASKET LIP, IT BEING NECESSARY ONLY TO WELD SAID SUPPORT MEMBER TO SAID TANK WALL FOR GOOD MECHANICAL CONNECTION WITHOUT REQUIRING A FLUIDTIGHT CONNECTION THEREBETWEEN, A MOUNTING PLATE AND A SHEATHED ELECTRIC HEATING ELEMENT EXTENDING NORMALLY OF SAID MOUNTING PLATE AND IN LIQUID-TIGHT RELATION THROUGH AN OPENING IN THE LATTER WITH AN ACTIVE HEATING PORTION PROJECTING FROM AN INNER SIDE OF SAID MOUNTING PLATE AND DISPOSED WITHIN SAID TANK AND A TERMINAL PORTION PROJECTING FROM THE OUTER SIDE OF SAID MOUNTING PLATE FOR CONNECTION TO A SOURCE OF ELECTRICAL ENERGY, A RING GASKET CONCENTRIC WITH AND DISPOSED WITHIN SAID SUPPORT MEMBER OPENING AND HAVING ONE SIDE SEATED AGAINST SAID ANNULAR LIP AND ITS OPPOSITE SIDE ENGAGING THE INNER SIDE OF SAID MOUNTING PLATE, AND MEANS CONNECTING SAID MOUNTING PLATE AND SAID SUPPORT MEMBER FOR DRAWING SAID MOUNTING PLATE TOWARD SAID GASKET LIP TO COMPRESS SAID GASKET THEREBETWEEN AND THUS SEAL SAID TANK OPENING AGAINST LEAKAGE OF FLUID THERETHROUGH. 